A wired local area network is typically a broadcasting network, and data transmitted from a node can be received by other nodes. Various nodes on the network share channels, which brings a great hidden security danger to the network. An attacker can capture all data packets on the network as long as he accesses the network to listen, and therefore key information is stolen.
In the prior art, the local area network LAN defined by the national standard GB/T 15629.3 (corresponding to IEEE 802.3 or ISO/IEC 8802-3) provides no data security method; and a data encryption protocol provided by the IEEE 802.1AE standard implements a safety transmission of data between nodes in the network based on a safety measure of hop-by-hop encryption. However, such safety measure brings a large computing load to switch devices in the local area network and the attacker is inclined to attack the switch devices; and also transmission delay of a data packet transmitted from a transmitting node to a destination node is increased, therefore the transmission efficiency of the network is decreased.
The wired local area network has a complicated topological structure and relates to large numbers of nodes, and therefore the data communication in the network is complicated. If a static key pair is distributed to the nodes in the local area network to establish a session key between the nodes, the distribution and updating processes will be extremely complicated. Therefore, the method of using the static key pair is not suitable for the establishment of the session key between the nodes.